Rinse beef, pat dry and chop into small cubes. Peel the onions and chop finely. Heat oil in a large pot, sautée the onions, add the beef and simmer for 8 minutes. Add the tomatoes. Dice the chile peppers finely, peel garlic and squeeze through a garlic press.
Add the peppers and garlic to the pot, alongwith the beans and let simmer, covered, for about 1 ½ hours. Rinse the scallions, cut the green parts off, cut into thin rings and mix in. Rinse and finely chop cilantro. Serve the chili in bowls garnished with a dollop of sour cream and the chopped cilantro.